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Always carry your mud boots

Progressive Forage Editor Lynn Jaynes Published on 15 July 2020

While several factors contribute to rainfall variability, if the tropical cyclone events were taken out of the data set, the annual mean rain from other events has not increased.

Show of hands – how many of you got the tractor stuck last season?

Wetter springs of 2019 turned into wetter summers in many parts of the U.S. Is that a trend? What’s behind it? There are voices that indicate it’s all due to man-made climate change. We’re going to ignore those voices for a moment and let those arguments be debated elsewhere. But the big question for agriculture is: Are we going to see more of that in 2020 and beyond?

I’ll just say up front, “I don’t know,” and apparently neither do climatologists. But there is something going on that’s interesting. A research white paper was released in June 2019 indicating a significant increase since the mid 20th century of a stalling frequency of tropical cyclones near the North American coast. The report states annual mean rainfall from tropical cyclones on the U.S. has risen significantly due to the increased stalling frequency. Annual mean rain for stalling tropical cyclones has more than doubled for 1983-2017, compared with 1948-1982. While several factors contribute to rainfall variability, if the tropical cyclone events were taken out of the data set, the annual mean rain from other events has not increased.

Katrina, Ike, Sandy, Harvey, Andrew, Irma, Michael, Camille – you probably recognize some of these storms. Let’s look at two recent ones: In 2018, Hurricane Florence moved at a pace of 1 mph and spent 53 hours in a 124-mile radius over the North Carolina coast. In 2017, Hurricane Harvey made landfall in Texas, traveling 5 mph, and in four days delivered record rainfall from the coast near Galveston Bay to the Houston area. It stalled over Texas for 100 hours. But Harvey didn’t leave just Texas reeling; it sent rainfall throughout Louisiana, Mississippi, Tennessee, Kentucky and the southern edges of Indiana and Ohio – as much as 60 inches in places. Damages ran to $125 billion (tying with Katrina).

Harvey was an example of storm stalling, where it was blocked by a high-pressure system in the western U.S. and a low-pressure system to the east. Those two systems were duking it out, trying to push-pull the storm different ways, but neither side was winning, so the storm stalled.

What causes stalls? Hurricanes produce their own spin, but they depend on larger wind patterns or “steering currents” to actually travel. Warmer climates reduce tropical wind patterns, slowing the travel. But, mind you, this is still being debated in the scientific community, and scientists have not linked climate change to the path or intensity of tropical storms, only the stalling patterns.

This is not a “the sky is falling” warning. This is not a “Yellowstone is gonna blow!” warning. This is not apocalyptic (so please, don’t run out and stock up on toilet paper). This is just to say, you might again this season and going forward see wetter seasonality. While the coastal cities garner the news headlines in these major weather events, agricultural areas along the eastern seaboard and through the Southeast and parts of the Midwest will likely suffer the effects.

I wish there was a way to funnel some of that to parched areas in the western half of the country.

So, for all you who are east of the Rocky Mountains, when I say, “How many of you are going to get your tractor stuck this season?” you can just raise your hands now.  end mark

Lynn Jaynes
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